By WERNER G. JAFFÉ AND C. A. ELVEHJEM
In a previous paper (1) results were presented to show that an alcoholic extract of liver produced a pronounced growth stimulation in rats fed a natural diet. The results showed that the activity was not due to any of the known vitamins and that yeast did not possess similar activity.
Bosshardt and collaborators have described a growth-stimulating effect of liver in rats (2), while Zucker and Zucker (3) described a syndrome involving kidney lesions in rats which was cured with liver. Liver has been shown to contain factors essential for the nutrition of the monkey (4) and for the growth stimulation of Streptococcus faecalis (5).
The present investigation was undertaken to improve the assay procedure with rats and to prepare liver fractions which would show higher activity.